Short-term tests on firing oil shale fuel applying low-temperature vortex technology

Abstract

The present paper provides experimental data from short-term, full-scale experiments of a high-pressure pulverized firing (PF) boiler, TP-67, firing oil shale after a retrofit to use vortex combustion (VC) technology. The essence of VC technology consists of the generation, at a lower part of the furnace, of a circulatory motion of gas relative to the horizontal axis (horizontal vortex) by rearranging the geometry of the combustion air injection and the fuel feeding into the combustion chamber. The tests were conducted at three boiler loads: 50% (160 t/h), 75% (240 t/h) and 100% (320 t/h). During the experiments, fuel samples of air-solids in the conduit and samples of bottom ash and fly ash from inertia dust collectors after the super heater (SH) and economizer (ECO), as well as fly ash from the electrostatic precipitator (ESP) of the first and second fields, were taken from both the left and the right sides of the boiler. The gas analysis was performed at the ESP exit. It was attempted to measure temperature distribution in the combustion chamber. Temperature measurements in the furnace using an infrared thermometer showed that the maximum temperature did not exceed 1150 °C, and there was slight temperature nonuniformity across the combustion chamber. During the tests, the ash distribution at different boiler ash discharge ports was obtained. Analysis of the bottom ash chemical composition showed a considerable increase in the amount of unburned carbon and marcasite Sp. The retrofit of the boiler to use VC technology did not result in a reduction in the amount of SO2 emissions, indicating an even weaker process of binding sulphur oxides in the furnace as compared to PF. © 2012 Estonian Academy Publishers.